Sony Zeiss 24mm - What is so special?

The Carl Zeiss 24mm with my NEX 7 is THE reason why I haven't fallen in love with my X100s yet.. X100s simply can't compete with the CZ24 in terms of sharpness. while sharpness isn't the only factor in IQ, I have to stop down the X100s to f4 to match the CZ24 at F1.8 in the center.

I'm starting to get more keepers with the X100s as I get more familiar with the camera. But the Carl Zeiss 24mm might be the best any mirrorless system or compact camera has to offer.